This invention relates to the field of extensions for trailers and the like. More specifically, the present invention relates to an apparatus for selectively extending outwardly and withdrawing a portion of the side of a trailer.
In the field of house trailers that are towed by motor vehicles, it has long been desired to provide a trailer that is relatively compact while it is being towed, but which can be expanded when parked to provide additional room. Numerous arrangements have been employed in the prior art to accomplish this result. For example, U.S. Pat. No. 4,557,518--Maclean et al. discloses a trailer with a pull-out side extension that is supported on bars that slide in and out of channels mounted on the underside of the trailer body. Other examples of trailers that are laterally expandable are disclosed in U.S. Pat. No. 2,581,192--La Fleur and U.S. Pat. No. 2,842,972--Houdart, both of which disclose rack-and-pinion mechanisms to move an extensible trailer body portion.
One common type of mechanism used in the prior art for extending or expanding trailer bodies is a cable and pulley mechanism, typically operated by a motor-driven drum or sheave. For example, U.S. Pat. No. 2,902,312--Ferrera discloses a trailer body comprising a fixed section and a movable section that slides laterally to double the width of the trailer when extended. The movable section has rollers that ride on rails at the front and back of the fixed section. Movement is effected by a cable and pulley mechanism operated by a motor-driven drum.
Other examples of expansible or extensible trailer bodies using cable and pulley mechanisms are disclosed in the following U.S. Pat. No. 1,471,549--Clement; U.S. Pat. No. 2,147,892--Gray; U.S. Pat. No. 3,482,716--Leadley; U.S. Pat. No. 3,672,238--Young et al.; U.S. Pat. No. 4,192,544--Patterson; and U.S. Pat. No. 4,270,791--Tann.
A relatively recent development in this field is the "slide-out" type of trailer extension, wherein an extensible portion of the side of the trailer body is carried on a pair of rails that are mounted for linear translation in a pair of hollow tubes or channels that are fixed to the bottom of the trailer body. In the prior art slide-out extension, the channels are joined by a first transverse member, on which is mounted an electric motor, and the rails are joined at one end by a second transverse member. The motor is connected to the second transverse member by an elongate drive screw, whereby rotation of the screw in a first direction pulls the rails outwardly from the channels to extend the slide-out portion, and rotation in the opposite direction pulls the rails into the channels to withdraw the slide-out portion back into the main portion of the trailer body.
While some of the prior art trailer extension and expansion devices have yielded satisfactory results, most have demonstrated a number of shortcomings. For example, most of the prior art devices must be installed at the time the trailer is manufactured, and cannot readily be adapted for retrofitting existing trailers. In addition, many of the prior art devices are cumbersome or inconvenient to operate, or have proven to be unreliable or noisy. The drive screw-operated extension, while suitable for retrofit applications, can be particularly noisy, and it is subject to binding due to bending of the rails as they are pulled into and out of the channels.
Accordingly, there has been a need for a trailer extension or expansion device that is sturdy and reliable, easily operated, and quiet in operation, and that can be either incorporated into a trailer body during manufacture, or retrofitted onto existing trailer bodies.